Pneumatic tire



Jan. 27, 1942. HALE ETAL 2,271,337

PNEUMATIC TIRE Filed Feb. 2, 1937 5 Sheets-Sheet 2 ATTOR Jan. 27, 1942. ETAL 2,271,337

PNEUMATIC TIRE Filed Feb. 2, 1937 1 3 Sheets-Sheet 5 Patented Jan. 27; 1942 PNEUMATIC TIRE James E. Hale, Akron,

Silver Lake, Ohi

and Albert Hargraves, -o assignor to The Firestone Tlre& Rubber Company, Akron, Ohio, a corporation 01 Ohio Application February 2, 1937, Serial No.l2 3,626 s Clziims. (Cl. 152- 209) This invention reln.tes to pneumatic tlres for vehlcle wheels, and more especially it; relatesto improved pneumatlc tires for tractors used for agricultural purposes under special conditlons wherein the pneumatic tires and steel tires heretofore used have been fouud not satisfactory.

The im'proved tire embodying the present inventlon is designed primarlly for use in agricultu ra.l operatlons that are ca.rrled out.in extremely Nwet .or muddy ground, and even in partly submerged soils. Such conditions obtaln normally in rice and sugar cane farming, and present a serious obstacle to the expeditious plowing of the land and the moving of the harvested crop therefrom. In the cane flelds conditions are further aggra.vated by the presence of much vegetable litter such as cane leaves and shucks upon the ground.

Vari0us 'expedients have been tried for meetlng the foregoing conditions, among which may be mentioned steel wheels provided with deep spade lugs. Traotoxs equipped with these tires will pull through mud under some conditions, but frequently cane shuck fitter on the ground ma.ts with the muddy soll in such a way as to form great balls of mud between the cleats or lugs on the wheel, sometimes to such an extent that the tractor can no longer pull its load. Furthermore, steel-cleated wheels frequently cut through the hard pan immecliately below the muddy soll, and bog down, thus causing serious loss of water als that point during the fioodingseason while rlce 1s growing, and ruining that portion 01 thedield for a year or more. Also, tractors equipped with steel wheels and spa.de lugs a17e not; permitted to tra.vel over highways and brldges with the result that their activitles are conflned strictly to the fields.

Another expedient that has been attempted is 1:0 equip the tractors with ordinary agricultural;

pneumatic tires, and mount thereon non-skid chalns equipped with deep lugs. Although such equipment provides adequate traction in deep mud, lt ls open to the same objections as steel wheels wlth cleats, namely, it cannot be used on the highways, and provides very bumpy riding. Moreover, the cha .lns are too heavy and unwleldy to conveniently put on and take off, they cut down the power cf the tractor, and frequently cause damage to the tires to which they are applled.

AI; the present .time the cane field farmers of Louisiana have found that the only satisfactory method of hauling ca.ne ab harvesting time ls by the use of mules. However, the initial cost of the mules is high and their use is confined to a few weeks of the year. During the remainder of the year they cor'xsume fodder without performing useful service.

The chiet objects of the invention are t o provide improved tlre equipment for hauling in deep mud or gumbo' which equipment issuitable for year wund operatioh; to provide tractor equipment of the character mentioned that will not infilct damage upon the soll; that; will not damage highways and consequently will be permitted to tra.vel thereove'ar; that will be seltcleaning and for that reason always will be able to provide traction in deep mud, muck, or gumbo;

that will niake for easy riding; that may be used on tractors for plowing, cultivating, and other farm operations, as well as for hauling; and that is subject to flotation whereby sinking into soft soll at.least is retarded. Other objects will be manifest.

Of the accompanying drawings:

Figure 1 ls a. perspective view of a pneumatlc tire casing constitutinghne embodiment of the invention;

Figure 2 is a. sectlon 011 the line 2-2 thereof;

Figure 3 is a fragmentary side elevation of the tlre shown in Figure 1;

Figure 4 ls a perspective view of another embodlment ot the invention;

Flgure 5 is a section 011 the line 55 cf Figure 4; Flgure 6 is a fragmentary side elevation ot the tlre shown in Figure 4;

Figure 7 ls a perspective view of still another embodiment of the invention;

Figure 8 ls a section on the line 8-8 of Figure 7; and

Figure 9 is a fragmentary side elevation of the tire shown in Figure 7.

Referrlng to Figures 1 to 8 of the drawings, there is shown a. pneumatic tire casing II) of relatively large size and having relatively thin side walls, the tire belng designed to operate at low inflation pressure in the manner of so-called balloon tires. ls formed with a relatively tall, upstanding traction element in the form of a zig-zag rib II that is continuous circumferentially of the tire the angles 01 the rlb being disposed ab the opposite lateral margins of the tread of the tire and the stralght reaches of. the rib extending obliquely across the tread. The rib l l is of such height that lts radial dimension constitutes approxi-. mately 20% cf the total radial height cf a transverse sectlon o1 the tire. In most tlres of this The tread portion of the tire type the helght or radial dimenslonof the rib will be about 2 lnches. As is clearly shown from the drawings, the height of the rib II is at least as great as the averaze wldth thereof. In transverse sectlon the rib II is tapered from a relatively wide base to a. relatlvely narmw flat top er crest, the arrangement providlng a draft that facllitates the wlthdrawing oi the rib from the mud in which lt normally operates. The tread of the tire is symmetricalgancl lt operates equally well when driven in either direction.

The rib H is rugged and aggressive, and because of its angular, zig-zag shape, each straight reach thereof laterally reinforces or buttresses the adjacent stralght reaches united to its respectlve ends wlth the result that the rib is enabled to wlthstand the severe strains of service condltions. Since the tire operates at low infiation pressure, there will be substantial flexure in the region thereof that is in contact wlth the ground, and such flexure provides suflicient relative movement between adjacent straight reaches of the rib H as to loosen any mud or soil that may become caked in the angular spaces defined by said straight reaches. The fact that the said angular spaces are open to the sides of the tread at their widest point simplifies the problem of ejecting mudfrom the tire. The rib II itself has at least a modicum of 'resilience, and slight flexing of the rib in combination with the shape of the laterally open areas defined by the rib, anti the tapered cross section of the latter, practically assure's that the tire will be self-cleaning. Because of their relatively large cross section, light body cor'1struction, and 10W inflation, the tires possess a buoyancy that prevents thern from sinking deeply into mud, notwithstanding the weight of the vehicle, with the result that less power is required for propelling the latter. The feature of the continuous circumferential rib II in combination with the inherent resilience f the tire makes for comfortable ricling both in the flelds and on pavements, and the tires achieve the other advantages set out in the foregoing statement of objects.

- Other embodiments of the invention, shown in Figures 4 to 9 inclusive, difier from that previously described primarily in the arrangement of the traction element upon the tread portion of the tire, other characteristics of the invention, such as relatively light weight, large cross section, relative tall traction element, and tapered section of the latter being present in all embodiments of the invention.

Referring now to Figures 4 to 6 inclusive, there is shown a tire casing I4 having a tread portion formed with a central circumferential lug or rib |5 that is arranged in zig-zag form, inwardly from the lateral margins of the tread. From each arris or exterlor angle of the rib I5, a lug I6 adjoined thereto extends t o the adjacentdateral margin of the tread, the lugs I6 on opposite sides of the central rib I5 being disposed in staggered relation to each other. The lugs I6 are parallel to each other and to the axis of the tire, and the tire operates equzilly as well when driven in one direction as when driven in the opposite direction.

The embodiment of the invention shown in Figures 7 to 9 comprises a tire casing I8, the tread portion of which is formed with a central circumferential rib I9 arranged in zig-zag fashion similar to rib I5 o! the previously describ.ed embodiment. From each arris or exterior Y angle of the rib I9, a lug 20 aq:ljoined thereto extends to the adjacent lateral margin of the tread, the lugs 20 011 opposite sides of the central.

5 rib I8 being disposed in staggered relation to each other. The lugs 20 also are disposed obliquely with relation to the central plane of the tire, and the lugs on opposite sides of the neutral rib extend in the same direction so that adjacent lugs are substantially parallel to each other. The arrangement is such that the tire 0perates equally as well when driven in one direction as when driven in the opposite direction, but one side of the tire will not clean itself qulte as readily as does the other side. In all other respects the tire achieves the several advantages inherent in the invention.

Other modiflcations may be resortecl to withauf. departing from the spirit of the invention or the scope of the appended claims.

What is claimed is:

1. A pneumatic tire for use on motor vehicles operatmg in soft, muddy soils, said tire comprising a flexible casing having a tread portion formed with a centrally disposed, circumierential, zig-zag traction ancl skid-resisting rib, said zig-zag rib being composed of straight components interseccing at apices on alternately oppasite sides of the central plane of the tire, ancl a series of lateral traction ribs on each side of the tire tread, said lateral ribs J'oining said zigzag ribs at said alternate apices, each o f said lateral ribs extending at right angles to the central plane of the tire and a1: an angle to each of the adjacent straight components of said zigzag rib.

2. A pneumatic tire foi use on motor vehicles posite lateral margins of the tread of the tire,

and laterally outwardly extending ribs integrally formed with the zig-zag rib at; the external angles thereof, each of said laterally extending ribs extending at right; angles to the central plane of the tire, said traction element having a height that is approximately one-flfth the total radial height of the cross section of the tire, the lateral faces of the traction element sloping toward each other outwardly from the base oi the element.

3. A pneumatic tire for use on motor vehicles operating in soft, muddy soils, said tire comprising a flexible casing having a tread portion formed with two series of lugs disposed transversely of the tire tread and extending Irom a region at one side of the center line of the tread to the respective lateral margins thereof, the lugs on one side of the tread being in staggered relation to those on the 0ther side of the tread, and all of said lugs being disposed normal tq the center line of the tire tread, and a centrally disposed circumferential zig-zag rib on the tread adjoined to the inner ends of said lugs, said lugs and rib having a transverse section that tapers from a relatively wide base to a relatively narrow flat top.

- JAMES E. HALE.

ALBERT HARGRAVES. 

